The current method for calculating grades in rubrics unnecessarily complicated and leads to errors in calculation of a students final grade. In order for a student to get the grade a lecturer expects, the rubric must be set up with a grade value of "0" for the first column in each of the criteria. otherwise the calculation will not work.
My suggested improvement is that the formula be changed to simply add up the marks obtained by the student and express it as a percentage of the total marks available.
The errors in the current system are only minor if the scale is 1,2,3,4 but if a lecturer sets the scale as 5,10,15, 20 for each level the errors become significant